Minerals 1 Minerals Minerals are: Naturally occurring, - - PowerPoint PPT Presentation

Minerals

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Minerals

 Minerals are:

• Naturally occurring,
• Inorganic,
• Solid,
• Have a definite chemical composition, and
• Have a definite crystal structure

 Mineral: Quartz, Pyrite  Not Mineral: cement, steel

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Minerals

 Inorganic:

• Not formed from living things or the remains the remains of

living things

 Coal is NOT a mineral because it comes from plants  Amber is NOT a mineral because it comes from tree

sap

 Pearl is NOT a mineral because it comes from

• ysters

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Minerals –

Chemical Composition

Name of Mineral Chemical Formula Chemical Name Elements and

• No. of molecules

Halite

NaCl Sodium Chloride

1- Sodium 1- Chlorine

Quartz

SiO2 Silicon Dioxide

1 – Silicon 2 – Oxygen

Pyrite

FeS2 Iron Sulfide

1- Iron 2- Sulfur

Hematite

Fe2O3 Iron Oxide

2- Iron 3- Oxygen

Magnetite

Fe3O4 Iron Oxide

3- Iron 4- Oxygen

Calcite

CaCO3 Calcium Carbonate

1- Calcium 1- Carbon 3- Oxygen

Graphite

C Carbon

1- Carbon

Sulfur

S Sulfur

1- Sulfur

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Minerals

 Solids:

• Have a definite volume and a definite shape
• Oil is not a mineral because it is liquid

 Crystal Structure:

• internal structure/arrangment of atoms
• Atom/molecules are arranged in repeating

patterns, characteristic geometry.

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Minerals – Crystal Structure

 Six basic crystal systems

Cubic/Isometric Galena, Halite, Pyrite Tetragonal Chalcopyrite Hexagonal Quartz, Calcite Orthorhombic Olivine, Topaz Monoclinic Mica, Gypsum Triclinic Feldspar, Turquoise

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Cubic/Isometric Pyrite, Halite Tetragonal Chalcopyrite Hexagonal Quartz, Calcite Orthorhombic Topaz Monoclinic Gypsum Triclinic Feldspar, Turquoise

Minerals – Crystal Structure

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Mineral Formation

 Minerals form

• When lava or magma cools to solidification
• When water evaporates dissolved minerals

remain

• When water is supersaturated with mineral

particles; minerals will settle out of the water an deposit as a “precipitate”

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Identifying Minerals

 Minerals can be identified by their physical and

chemical properties.

• Physical Properties:
• Color
• Streak
• Luster
• Hardness
• Cleavage or Fracture
• Density
• Chemical Properties
• Reaction to Acid

 Determined by chemical composition and

structure

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Physical Properties

 Color

• Malachite-green
• Sulfur-yellow
• Not a reliable property; some minerals

can be many different colors.

• Quartz-clear, pink, purple, white, grey-

brown…

• Hematite-black, grey, reddish brown, dark

red

• Color may vary due to:
• Natural coloring agents - impurities
• Weathering; exposure to the environment`

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Physical Properties

 Streak

• The color of the mineral in its powdered form.
• Determined by using a streak plate

 Hematite: reddish brown  Quartz: White/colorless

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Physical Properties

 Luster

• The way a mineral shines/reflects light from its

surface.

 Metallic: reflects light like the surface of a

polished metal

• Galena, Pyrite, Graphite, Magnetite…

 Non Metallic: reflects light in more subtle ways

• Pearly-Mica, Glassy-Quartz, Dull/Earthy-Kaolinite,

Waxy-Talc, Brilliant-Diamond.

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Physical Properties

 Hardness

• A measure of how

easily a mineral can be scratched.

• Softest mineral is

Talc

• Hardest mineral is

Diamond

• Determined by a

minerals internal structure, strength of bond between atoms

Hardness Name of Mineral 1 Talc 2 Gypsum 3 Calcite 4 Fluorite 5 Apatite 6 Feldspar 7 Quartz 8 Topaz 9 Corundum 10 Diamond

Common Objects

2.5 Fingernail 3.5 Copper 4.5 Iron Nail 5.5 Glass 6.5 Steel File 7 Streak Plate

Mohs Hardness Scale

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Testing Hardness

Hardness Name of Mineral 1 Talc 2 Gypsum 3 Calcite 4 Fluorite 5 Apatite 6 Feldspar 7 Quartz 8 Topaz 9 Corundum 10 Diamond Common Objects

2.5 Fingernail 3.5 Copper 4.5 Iron Nail 5.5 Glass 6.5 Steel File 7 Streak Plate

Mohs Hardness Scale

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Physical Properties

 Cleavage

• When a mineral splits/breaks along

smooth flat surfaces

• Determined by atomic structure of

mineral

• Cleavage is the way a mineral breaks
• Crystal Shape is the way a crystal

grows

• Mica - One direction; sheet
• Galena – Three; cubic shape

 Fracture

• When a mineral breaks unevenly into

curved or irregular pieces with a rough and jagged surfaces

• Sulfur, bauxite, hematite, quartz

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 Crystal Shape and Fracture

Physical Properties

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Physical Properties

 Density or Heft

• Minerals have different densities,

and vary in weight given the same sample size

 Special Properties

• Lodestone-Magnetite; is naturally

magnetic

• Iceland Spar-Calcite; produces

double refraction

• Pitchblend; radioactive

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Chemical Properties

 Effervescence

• Calcite reacts with HCl.
• It forms bubbles of CO2(g)

 Oxidation – a reaction between metals and oxygen.

• Iron (Fe) + oxygen = Rust
• Metal is weakened by change
• Copper (Cu) + oxygen = copper oxide
• Creates a greenish coating; metal is not weakened

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Uses of Minerals

 Ore

• A mineral that contains metals and nonmetals that

can be mined and removed in usable amounts; for a profit

• Metals- elements that have a shiny surfaces, are able to

conduct heat and electricity, and are malleable.

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Uses of Minerals

 Ore - Metals

Iron – Hematite/Magnetite Aluminum - Bauxite Copper - Chalcopyrite/Malachite Lead - Galena Silver - Argenite Gold - Gold

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Uses of Minerals

 Nonmetals

• Elements that have dull

surfaces and are poor conductors of heat and electricity

• Halite-NaCl-Salt
• Gypsum-Drywall, chalk
• Sulfur-Matches
• Talc-Powder
• Graphite-Pencil Lead
• Calcite-Cement
• Kaolinite-Bricks

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Uses of Minerals

 Alloy

• A mixture of two or more metals or a

mixture of metals and nonmetals

• Tin+Copper= Bronze
• Copper+Zinc= Brass
• Iron+Chromium+Limestone= Steel
• Lead+Tin= Pewter

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Uses of Minerals

 Gems

• Minerals that have desirable qualities
• Hardness, color, luster, clarity, durability, rarity
• Precious Stones:
• Diamond, Rubies, Sapphires, Emeralds
• Semi-Precious Stones:
• Amethyst

Garnet Topaz

• Gems that are not minerals
• Pearls

Amber

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